Статті в журналах з теми "Piling (Civil engineering) Testing Mathematical models"
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1
Andjelkovic, Vladimir, Zarko Lazarevic, and Velimir Nedovic. "Application of analogous models in civil engineering." Facta universitatis - series: Architecture and Civil Engineering 9, no. 3 (2011): 395–405. http://dx.doi.org/10.2298/fuace1103395a.
Повний текст джерелаАнотація:
The paper describes the results of making the mathematical and physical models of the authors, by using analogous methods and materials. There is the mathematical rock mass deformability model as a base for foundation engineering a concrete arch dam and the physical rock slope model which was tested by loading until failure and the results were compared with the calculation procedure. In the first example the correlation is established between the static and the analogous dynamic in situ investigations for creating the mathematical rock mass deformability model. In the second example there is application of the analogous materials for the discontinuity shearing simulation on the physical slope model. The results of the geotechnical in situ investigations and laboratory testing carried out in the Institute for Development of Water Resources "Jaroslav Cerni" in Belgrade were used for making the models.
2
Abdallah, Wafaa, Jacqueline Saliba, Ziubir-Mehdi Sbartaï, Marwan Sadek, Fadi Hage Chehade, and S. Mohammed ElAchachi. "Reliability analysis of non-destructive testing models within a probabilistic approach." MATEC Web of Conferences 281 (2019): 04003. http://dx.doi.org/10.1051/matecconf/201928104003.
Повний текст джерелаАнотація:
The diagnosis of reinforced concrete is essential to detect the degradation and thus maintain the structural performance of civil engineering structures. This paper aims to establish a mathematical relationship between the ultrasonic pulse velocity UPV (considered as an observable variable) and two concrete properties indicators (compressive strength fc and water content W) within a probabilistic framework. Synthetic simulations are proposed to derive a conversion model between the statistical properties of the output and the input parameters for a reinforced concrete structure by taking into account spatial variability of concrete.
3
Bouaanani, Najib, Patrick Paultre, and Jean Proulx. "Dynamic response of a concrete dam impounding an ice-covered reservoir: Part I. Mathematical modelling." Canadian Journal of Civil Engineering 31, no. 6 (December 1, 2004): 956–64. http://dx.doi.org/10.1139/l04-075.
Повний текст джерелаАнотація:
This paper examines the dynamic response of a concrete dam impounding an ice-covered reservoir and subjected to forced-vibration testing. The analytical research presented is a follow-up to an extensive dynamic testing program carried out on a 84-m high concrete gravity dam located in northeastern Quebec, Canada, under harsh winter conditions, including a 1.0- to 1.5-m-thick ice sheet covering the reservoir. One of the major challenges encountered when analyzing ice-dam-reservoir-foundation interaction is modelling the complex nature of the ice and the boundary conditions governing reservoir motion. The problem is further complicated because there are little or no appropriate experimental data and observational evidence relevant to ice-dam interaction processes. Some of these challenges are addressed herein using a two-dimensional analytical approach, which investigates the effects due to ice cover, water compressibility, and reservoir bottom absorption. A frequency-domain substructure method technique is used and a new boundary condition along the ice-cover-reservoir interface is proposed. The technique developed is implemented in a finite element code specialized in the seismic analysis of concrete dams. Numerical results are discussed in the companion paper in this issue. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice-structure interaction, fluid-structure interaction, forced-vibration testing, finite elements modelling.
4
Chang, Ying, Lin Zhao, and Yaojun Ge. "Theoretical and testing investigation of wind–rain coupling loads on some typical bluff bodies." Advances in Structural Engineering 22, no. 1 (June 18, 2018): 156–71. http://dx.doi.org/10.1177/1369433218781953.
Повний текст джерелаАнотація:
The article presents a mathematical theoretical framework and fitting parameters with aspects of joint probability distribution of wind and rain, separate wind and rain action, and coupled wind and rain effects on steady and unsteady forces acting on some typical bluff bodies. Gumbel and copula functions were first selected to describe the joint probability distribution of wind speed and rain intensity. Then, two models, a raindrop impact model and an equivalent air density model, were adopted to quantify the loading action considering only separate wind and rain action, and simplified coupled effects with superimposition of wind and rain show that it would be accurate enough to neglect separated rain influence in steady wind and rain loading conditions. Furthermore, wind tunnel testing has been carried out under coupled wind and rain conditions with the help of a high-precision raining simulation system in TJ-1 wind tunnel on various reduced-scale models with some typical cross sections, such as circular and rectangular, thin plate, and streamlined box, and their aerodynamic loading and wind–rain-induced performance have been systematically compared. It has thus been found that the coupling effects of wind and rain should not be neglected in steady and unsteady force models.
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Buchta, Vojtech. "Experimental Testing the Interaction of Fiber-Concrete Foundation Slab and Subsoil and Compare the Results with Numerical Models." Advanced Materials Research 1020 (October 2014): 227–32. http://dx.doi.org/10.4028/www.scientific.net/amr.1020.227.
Повний текст джерелаАнотація:
We solve interaction between the foundation base and the subsoil in civil engineering quite often. For the determination of stress in foundation structure is needed to determine the influence of the stiffness respectively pliability of subsoil to structural internal forces, and vice versa, how the stiffness of the foundation structure affects the resulting subsidence. It is necessary to compare the mathematical models with the actual behavior of the real structure. In 2013 was realised static load on testing equipment in the campus of Faculty of Civil Engineering, VSB–TU Ostrava. Dimensions of test element was 2000 x 2000 x 170 mm and the concrete slab was reinforced with steel fiber type DRAMIX 3D 65/60B6. During measurements were performed and recorded: tensometrical measurement on the surface of the slab, tensometrical measurement inside the slab, measuring the vertical load, measurement of the vertical deformation, measuring the stress on the interface of the slab and soil. Were also developed numerical models of this test in program Nexis. Comparison the test results with numerical models are presented in this paper. [1,9]
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Li, Yi, Chao Li, Qiu-Sheng Li, Yong-Gui Li, and Fu-Bin Chen. "Refined Mathematical Models for Across-Wind Loads of Rectangular Tall Buildings with Aerodynamic Modifications." International Journal of Structural Stability and Dynamics 21, no. 09 (May 20, 2021): 2150131. http://dx.doi.org/10.1142/s0219455421501315.
Повний текст джерелаАнотація:
This paper aims to systematically study the across-wind loads of rectangular-shaped tall buildings with aerodynamic modifications and propose refined mathematic models accordingly. This study takes the CAARC (Commonwealth Advisory Aeronautical Research Council) standard tall building as a benchmark model and conducts a series of pressure measurements on the benchmark model and four CAARC models with different round corner rates (5%, 10%, 15% and 20%) in a boundary layer wind tunnel to investigate the across-wind dynamic loads of the typical tall building with different corner modifications. Based on the experimental results of the five models, base moment coefficients, power spectral densities and vertical correlation coefficients of the across-wind loads are compared and discussed. The analyzed results shown that the across-wind aerodynamic performance of the tall buildings can be effectively improved as the rounded corner rate increases. Taking the corner round rate and terrain category as two basic variables, empirical formulas for estimating the across-wind dynamic loads of CAARC standard tall buildings with various rounded corners are proposed on the basis of the wind tunnel testing results. The accuracy and applicability of the proposed formulas are verified by comparisons between the empirical formulas and the experimental results.
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Papadimitriou, Stavros, and Charisma F. Choudhury. "Transferability of Car-Following Models Between Driving Simulator and Field Traffic." Transportation Research Record: Journal of the Transportation Research Board 2623, no. 1 (January 2017): 60–72. http://dx.doi.org/10.3141/2623-07.
Повний текст джерелаАнотація:
During the past few decades, there have been two parallel streams of driving behavior research: models using trajectory data collected from the field (using video recordings, GPS, etc.) and models using data from driving simulators (in which the behavior of the drivers is recorded in controlled laboratory conditions). Although the former source of data is more realistic, it lacks information about the driver and is typically not suitable for testing effects of future vehicle technologies and traffic scenarios. In contrast, driving behavior models developed with driving simulator data may lack behavioral realism. However, no previous study has compared these two streams of mathematical models and investigated the transferability of the models developed with driving simulator data to real field conditions in a rigorous manner. The current study aimed to fill this research gap by investigating the transferability of two car-following models between a driving simulator and two comparable real-life traffic motorway scenarios, one from the United Kingdom and the other one from the United States. In this regard, stimulus–response–based car-following models were developed with three microscopic data sources: ( a) experimental data collected from the University of Leeds driving simulator, ( b) detailed trajectory data collected from UK Motorway 1, and ( c) detailed trajectory data collected from Interstate 80 in California. The parameters of these car-following models were estimated by using the maximum likelihood estimation technique, and the transferability of the models was investigated by using statistical tests of parameter equivalence and transferability test statistics. Estimation results indicate transferability at the model level but not fully at the parameter level for both pairs of scenarios.
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Kimball, Colin E. "Evaluating Groundwater Pollution Susceptibility of Dust Suppressants and Roadbed Stabilizers: Case Study of a Petroleum-Based Product." Transportation Research Record: Journal of the Transportation Research Board 1589, no. 1 (January 1997): 64–69. http://dx.doi.org/10.3141/1589-11.
Повний текст джерелаАнотація:
Current environmental regulations have prompted regulatory officials, users, and manufacturers of roadbed stabilizers and dust suppressants to evaluate the environmental impact of these products to ensure that human health and the environment are not compromised through their use. Because roadbed stabilizers and dust suppressants are inherently designed to prevent dust emissions and erosion, this study focuses on evaluating the groundwater pollution susceptibility of roadbed stabilizers and dust suppressants. Current techniques used in evaluating hazardous waste sites to estimate the fate and transport of constituents in the subsurface are useful for evaluating roadbed stabilizers and dust suppressants. Chemical properties of roadbed stabilizers and dust suppressants along with generic soil property parameters can be incorporated into screening-level mathematical models to estimate constituent target-level concentrations in groundwater. These techniques were applied to a petroleum-based soil stabilizer and dust suppressant known as Pennz-Suppress D (petroleum-based product). The content of Environmental Protection Agency priority pollutants was determined by laboratory analysis. Further testing with leachate extraction methods provided additional data on leachability of the petroleum-based products under assumed worst-case conditions. Mathematical modeling was used to qualify the results. Groundwater pollution susceptibility results indicate a low risk for the product to adversely affect groundwater.
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Baltrušaitis, Andrius, Audrius Vaitkus, and Juris Smirnovs. "Asphalt Layer Density and Air Voids Content: GPR and Laboratory Testing Data Reliance." Baltic Journal of Road and Bridge Engineering 15, no. 3 (August 14, 2020): 93–110. http://dx.doi.org/10.7250/bjrbe.2020-15.486.
Повний текст джерелаАнотація:
The assurance of asphalt pavement layer compaction, expressed by ratio between field and laboratory bulk density and air voids content, is one of the main criteria of the durability of asphalt road pavement. Destructive measures should be applied and cores should be taken from the asphalt pavement seeking to determine the representative compaction level of the constructed asphalt layers. New methods are constantly being sought for fast, non-destructive and accurate asphalt layer density and air void determination on road. Ground Penetrating Radar (GPR) can allow determining the qualitative characteristics of asphalt pavement across the entire length of the road without causing damage to the road structure. Relative dielectric permittivity, usually called dielectric value or constant, is the leading property used in GPR applications on road pavement surveys. This article presents GPR measurement results from asphalt base and binder layers of four test sections. GPR measurements were conducted immediately after the end of asphalt layer compaction process. Test points on each layer were selected and density, air void content were determined by drilling cores and testing them in the laboratory. To estimate asphalt layer density and air void content, GPR data were analysed using different existing mathematical models. To justify the reliability of the data measured by GPR, results were checked by comparing them with the results measured directly on cores taken from the asphalt pavement layers.
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Manikrishna*, K. S. G. V., Veluru Sridevi, Sri Himaja Pamu, M. Tukaram Bai, and K. S. NV Prasad. "Biosorption of Malachite Green Dye from Wastewater with Henfeathers -Analysis of Various Mathematical Models Wrt Continuous Adsorption." International Journal of Innovative Technology and Exploring Engineering 10, no. 10 (August 30, 2021): 15–23. http://dx.doi.org/10.35940/ijitee.j9387.08101021.
Повний текст джерелаАнотація:
In recent years, the remediation of hazardous organic dye-contaminated aquatic habitats has been a key research priority for environmental and chemical engineers. The goal of this research was to see how well malachite green adsorbs from waste water in a continuous column system having fixed bed. A biosorbent made from waste materials such as hen feathers has been shown to extract the water-soluble malachite green colour from waste water. The adsorption potential of malachite green dye ions in a continuous flow adsorption column is investigated in this work. The hen feathers' performance in the fixed bed column was assessed under a variety of operating circumstances, including bed height in the range 6-10cm; flow in the range 4-12ml/min, and starting concentration (10-30 mg/l). In comparison to other testing settings, the bed height (8cm), flowrate (12ml/min), and maximum input concentration (20mg/l) resulted in the highest malachite green absorption of 2.829mg/g. The column experimental data collected under various conditions was evaluated using three distinct models namely 1. Bohart-Adams model, 2 Yoon-Nelsons model, and 3 BDST model, all of which produced a decent estimation of the breakthrough curve. The findings from the Yoon-nelson and BDST models, on the other hand, were more favourable. The several characteristics of the hen feathers were studied using FTIR studies. The activated hen feather powder was a successful potential bio sorbent for the malachite green from aqueous phase.
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Stara, Marie. "Testing of Pre-Stressing Masonry Wall with Using Different Thickness of Anchor Plates." Advanced Materials Research 1082 (December 2014): 211–15. http://dx.doi.org/10.4028/www.scientific.net/amr.1082.211.
Повний текст джерелаАнотація:
Contribution deals with experimental measurements of deformations in the place exposed to local load caused by additional pre-stressing. The measurements are made at the masonry brick corner built in the laboratory equipment. The laboratory equipment was designed at Faculty of Civil Engineering VŠB – TU Ostrava for measurement tri-axial stress-strain conditions in masonry. In this brick corner one pre-stressing bar is placed. And on the pre-stressing bar is anchored to the anchor plate which transfer pre-stressing forces to the masonry. The thickness of brick corner is 440mm and anchor plate will be used about thickness 10, 20 and 30mm. Mathematical modelling of brick corner is based on finite element method using software ANSYS and then the results are compared with results of laboratory tests. On the basis of these results it should be possible to improve the models and to approach closer to the accurate and at the same time simple procedure for design of pre-stressed masonry.
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Papa, Umberto, Salvatore Ponte, and Giuseppe Del Core. "Conceptual Design of a Small Hybrid Unmanned Aircraft System." Journal of Advanced Transportation 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/9834247.
Повний текст джерелаАнотація:
UAS (Unmanned Aircraft System) technologies are today extremely required in various fields of interest, from military to civil (search and rescue, environmental surveillance and monitoring, and entertainment). Besides safety and legislative issues, the main obstacle to civilian applications of UAS systems is the short time of flight (endurance), which depends on the equipped power system (battery pack) and the flight mission (low/high speed or altitude). Long flight duration is fundamental, especially with tasks that require hovering capability (e.g., river flow monitoring, earthquakes, devastated areas, city traffic monitoring, and archeological sites inspection). This work presents the conceptual design of a Hybrid Unmanned Aircraft System (HUAS), merging a commercial off-the-shelf quadrotor and a balloon in order to obtain a good compromise between endurance and weight. The mathematical models for weights estimation and balloon static performance analysis are presented, together with experimental results in different testing scenarios and complex environments, which show 50% improvement of the flight duration.
13
Bouaanani, Najib, Patrick Paultre, and Jean Proulx. "Dynamic response of a concrete dam impounding an ice-covered reservoir: Part II. Parametric and numerical study." Canadian Journal of Civil Engineering 31, no. 6 (December 1, 2004): 965–76. http://dx.doi.org/10.1139/l04-076.
Повний текст джерелаАнотація:
This paper presents a numerical and parametric study of the effect of an ice cover on the dynamic response of a concrete dam using the approach proposed in the companion paper in this issue. The method was programmed and implemented in a finite element code specialized for the seismic analysis of concrete dams. The 84-m-high Outardes 3 concrete gravity dam in northeastern Quebec was chosen as a model for this research. Some basic aspects of the numerical model are established in this paper and we show that the ice cover affects the dynamic response of the ice–dam–reservoir system. Main features of this influence are emphasized and discussed in a parametric study through the analysis of: (i) acceleration frequency response curves at the dam crest, (ii) hydrodynamic frequency response curves inside the reservoir, and (iii) the hydrodynamic pressure distribution on the upstream face of the dam. Key words: gravity dams, concrete dams, ice, reservoirs, mathematical models, ice–structure interaction, fluid–structure interaction, forced-vibration testing, finite elements modelling.
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Wang, Fangru, and Catherine L. Ross. "Machine Learning Travel Mode Choices: Comparing the Performance of an Extreme Gradient Boosting Model with a Multinomial Logit Model." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 47 (May 14, 2018): 35–45. http://dx.doi.org/10.1177/0361198118773556.
Повний текст джерелаАнотація:
The multinomial logit (MNL) model and its variations have been dominating the travel mode choice modeling field for decades. Advantages of the MNL model include its elegant closed-form mathematical structure and its interpretable model estimation results based on random utility theory, while its main limitation is the strict statistical assumptions. Recent computational advancement has allowed easier application of machine learning models to travel behavior analysis, though research in this field is not thorough or conclusive. In this paper, we explore the application of the extreme gradient boosting (XGB) model to travel mode choice modeling and compare the result with an MNL model, using the Delaware Valley 2012 regional household travel survey data. The XGB model is an ensemble method based on the decision-tree algorithm and it has recently received a great deal of attention and use because of its high machine learning performance. The modeling and predicting results of the XGB model and the MNL model are compared by examining their multi-class predictive errors. We found that the XGB model has overall higher prediction accuracy than the MNL model especially when the dataset is not extremely unbalanced. The MNL model has great explanatory power and it also displays strong consistency between training and testing errors. Multiple trip characteristics, socio-demographic traits, and built-environment variables are found to be significantly associated with people’s mode choices in the region, but mode-specific travel time is found to be the most determinant factor for mode choice.
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Toodesh, Reenu, Sandra Verhagen, and Anastasia Dagla. "Prediction of Changes in Seafloor Depths Based on Time Series of Bathymetry Observations: Dutch North Sea Case." Journal of Marine Science and Engineering 9, no. 9 (August 27, 2021): 931. http://dx.doi.org/10.3390/jmse9090931.
Повний текст джерелаАнотація:
Guaranteeing safety of navigation within the Netherlands Continental Shelf (NCS), while efficiently using its ocean mapping resources, is a key task of Netherlands Hydrographic Service (NLHS) and Rijkswaterstaat (RWS). Resurvey frequencies depend on seafloor dynamics and the aim of this research is to model the seafloor dynamics to predict changes in seafloor depth that would require resurveying. Characterisation of the seafloor dynamics is based on available time series of bathymetry data obtained from the acoustic remote sensing method of both single-beam echosounding (SBES) and multibeam echosounding (MBES). This time series is used to define a library of mathematical models describing the seafloor dynamics in relation to spatial and temporal changes in depth. An adaptive, functional model selection procedure is developed using a nodal analysis (0D) approach, based on statistical hypothesis testing using a combination of the Overall Model Test (OMT) statistic and Generalised Likelihood Ratio Test (GLRT). This approach ensures that each model has an equal chance of being selected, when more than one hypothesis is plausible for areas that exhibit varying seafloor dynamics. This ensures a more flexible and rigorous decision on the choice of the nominal model assumption. The addition of piecewise linear models to the library offers another characterisation of the trends in the nodal time series. This has led to an optimised model selection procedure and parameterisation of each nodal time series, which is used for the spatial and temporal predictions of the changes in the depths and associated uncertainties. The model selection results show that the models can detect the changes in the seafloor depths with spatial consistency and similarity, particularly in the shoaling areas where tidal sandwaves are present. The predicted changes in depths and uncertainties are translated into a probability risk-alert map by evaluating the probabilities of an indicator variable exceeding a certain decision threshold. This research can further support the decision-making process when optimising resurvey frequencies.
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Radoičić, Goran, and Miomir Jovanović. "Influence of a synchronized human dynamic load on vibrations of machine structures." Journal of Applied Engineering Science 19, no. 1 (2021): 237–45. http://dx.doi.org/10.5937/jaes0-28214.
Повний текст джерелаАнотація:
This paper contributes to the research of rhythmic behavior of a group of people, which, more or less synchronized, moves or jumps on a thin and elastic plate, thus performing a dynamically variable load. The analysis of the rhythmic behaviour of the crowd carried out on the basis of the experimental testing on the special steel test platform. The experiment consisted of sixteen measurements of live force and acceleration of the test platform. The dynamic loads caused by the mass of the human crowd and individuals had different intensities. The measurements of acceleration of the test platform were performed in order to estimate how the live human force influences on vibrations of machine structures. This research allows us to gain a picture of how serious the threats are from some human actions on the support structure of machines that are handled when performing works in industry, construction or mining. On the basis of these experiments, the mathematical models of the equivalent excitation forces were developed. The measured accelerations of the test platform tread surface and calculated dynamic coefficients of human force indicate that similar actions can seriously endanger balance of the support structure of some machine, and even, for example, can cause the main girder of the bridge crane to fall out. This and similar experiments allow us to formulate appropriate models of excitation loads by human force, which can then be used in simulation analyses in order to develop future systems of electronic protection of machines structures from adverse events.
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Ali, Jafar, and Debasish Bandyopadhyay. "Experimental validation of the proposed technique for condition monitoring of structure using limited noisy modal data." International Journal of Structural Integrity 11, no. 1 (August 15, 2019): 45–59. http://dx.doi.org/10.1108/ijsi-02-2019-0013.
Повний текст джерелаАнотація:
Purpose Condition monitoring (CM) of structures is important from safety consideration. Damage detection techniques, using inverse dynamic approaches, are important tools to improve the mathematical models for monitoring the condition of structure. Uncertainties in the measured data might lead to unreliable identification of damage in structural system. Experimental validation is crucial for establishing its practical applicability. The measurement of dynamic responses at all degrees of freedom (DOFs) of a structure is also not feasible in practice. In addition the effect of these uncertainties and constraint of limited measurement are required to be studied based on experimental validation. This paper aims to discuss these issues. Design/methodology/approach Proposed numerical model based on measured natural frequencies and mode shapes is found suitable for CM of framed structures in the framework of finite element model with limited dynamic responses. The structural properties, namely, axial rigidity and bending rigidity are identified at the element level in the updated models of the system. Damage at the element level is identified by comparing the identified structural parameters of the updated model of the system with those of the undamaged state. Proposed numerical model is suitable for practical problem, as it is able to identify the structural parameters with limited modal data of first few modes, measured at selected DOFs. Findings The model is able to identify the structural damage with greater accuracy from the noisy dynamic responses even if the extent of damage is small. Experimental studies, on simple cantilever beams, establish the potential of the proposed methods for its practical implementation. Research limitations/implications The greater random noise will lead to unreliable identification of structural parameters as observed. Thus, filtering of noise technique may be required to be adopted prior to consideration of the measured data in the proposed identification approach. Practical implications Requirement of higher modal data seems to be difficult in case of real life practical problem. Thus, simulation technique like condensation or SEREP technique may be adopted. Social implications Structural health monitoring of infrastructural system is significantly important. CM of those structures from global response with limited measured data seems to be an effective tool to ensure safety and durability of structures. Originality/value The modal testing and subsequent extraction of modal data have been carried out at the authors’ laboratory. The numerical code based on inverse dynamic approach has been developed independently with original contribution.
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Li, Huo-Kun, Yi-Wei Zhong, Bo-Wen Wei, Lei Du, and Gang Wang. "Beat vibration mechanism of a sluice pier under high-speed flood discharge excitation." Journal of Low Frequency Noise, Vibration and Active Control 39, no. 1 (March 6, 2019): 28–43. http://dx.doi.org/10.1177/1461348419834115.
Повний текст джерелаАнотація:
The sluice pier prototype vibration test conducted in China Shuhe Hydropower Station shows that the vibration response of the measuring points exhibits a special form of vibration, which demonstrates intermittency and impact under high-speed flood discharge excitation. The waveform envelope increases or decreases sharply with time and shows the formation of beat vibration. Research on the mechanism of this type of vibration is rare. To analyze the characteristics and causes of the obvious beat phenomenon in the testing of the sluice pier prototype, we conduct research in the following manner. First, mathematical models of synthetic signals are built to analyze the influences of initial phase difference, frequency ratio, and amplitude ratio and determine the beat vibration formation condition. Second, the stochastic subspace identification method is used to identify the operational modal parameters (including the vibration order, frequency, damping ratio, and mode of vibration) on the basis of the measured prototype dynamic response. Last, the internal causes of the beat vibration phenomenon are analyzed based on the combination of the formation conditions of apparent beat vibration. Results show that the vibration of Shuhe sluice pier is dominated by the first two frequency components. The vibration frequency ratio is between 0.928 and 0.962 and satisfies the necessary conditions of beat vibration. The amplitude ratio is between 0.66 and 1.63 and thus makes the waveforms of beat vibration highly evident.
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Aksenov, Ivan, and Aleksandr Konstantinov. "TEMPERATURE DEFORMATIONS OF PVC WINDOW PROFILES WITH REINFORCEMENT." International Journal for Computational Civil and Structural Engineering 18, no. 2 (June 24, 2022): 98–111. http://dx.doi.org/10.22337/2587-9618-2022-18-2-98-111.
Повний текст джерелаАнотація:
Modern window structures made of PVC profiles can experience significant temperature deformation during both winter and summer operation. This effect is not considered in the current engineering methods of PVC windows calculation, which causes a number of problems in their operation (freezing and blowing through the windows, the failure of fittings, etc.). The use of laboratory methods of testing windows for temperature loads is limited due to their labor intensity and the high cost of testing equipment. We propose to develop an engineering method for calculating the mechanical operation of PVC windows under the action of temperature loads, which can be used at an early stage of design. One of the stages of its creation is a theoretical description of the temperature deformation of a PVC window profile when it works together mechanically with a reinforcing core. The article describes the nature of the forces transmitted by the PVC profile on the core during thermal bending (the case of temperature deformation at negative outside temperatures is considered). It was proposed to decompose these forces into two components: longitudinal, caused by different values of temperature shrinkage of PVC profile and reinforcing core, and transverse, caused by thermal bending of PVC profile. Mathematical models have been developed to calculate both force components and temperature deformation of the profile at different numbers and spacing of attachment points. A physical model has been proposed for implementation in the numerical calculation program, which allows a more accurate description of the temperature deformation of a long profile. Calculation of the test problem according to the proposed methodology and by means of full-fledged three-dimensional finite-element modeling in the COMSOL Multiphysics program was performed. A comparison of the results showed a discrepancy of less than 10%. It was found that the key influence on the deformations of PVC window profiles with a reinforcing core will have characteristics of the outermost joints "PVC profile – reinforcing core", because the greatest forces arise in them under the action of temperature loads.
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Snitynskyy, Volodymyr, Volodymyr Burtak, Bohdan Diveyev, Orest Horbay, Ruslan Humenyuk, and Ivan Kernytskyy. "Dynamic properties of screw-bolts connections of sowing machine." Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 28, no. 4 (December 29, 2019): 584–93. http://dx.doi.org/10.22630/pniks.2019.28.4.53.
Повний текст джерелаАнотація:
A vehicle is a complicated system under the influence of vibration caused by an inequality of the road surface, variable speed, unbalance of the rotating elements. The main factors influencing the relaxation of threaded connections (TC) are the amplitude, frequency and gradient of vibration. Although the frequencies of these oscillations are distributed over a wide range, the general effects of dynamic loading on bolted connections are similar. Main effects: (1) loosening the nut/bolt and (2) failure due to fatigue failure. The analysis of the technological process of agricultural machinery shows that the main external factors influencing their work are the profile of the surface of the field, the hardness and moisture of the soil, the speed of the unit, the instability of the engine, the traction of the wheels of the tractor and others. To study the integrity of TC, which is tested on the stand, consider the design scheme of nonlinear oscillations of the design in the presence of gaps in the TC. The study was conducted in two modes of movement of the drill: with tightened bolts and weakened bolts. For the survey, the method of spectral analysis of multidimensional periodically non-stationary random signals was used. In the process of testing, the dynamic loading of bolted joints installed on the respective knots and components of the drill was evaluated. From the conducted research it follows that the maximum vibrations acting on the TC of the drill may be in the vicinity of high-frequency resonances of TC. In parallel, nonlinear mathematical models of the oscillations of the seeder and the weakened TC were developed. The theoretical results qualitatively correspond to the experimental data.
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Zhukov, Alexey, Ekaterina Bobrova, Ivan Popov, and Demissie Bekele Аrega. "SYSTEM ANALYSIS OF TECHNOLOGICAL PROCESSES." International Journal for Computational Civil and Structural Engineering 17, no. 4 (December 26, 2021): 73–82. http://dx.doi.org/10.22337/2587-9618-2021-17-4-73-82.
Повний текст джерелаАнотація:
The article discusses ways to solve engineering problems in the study of technological processes using methods of system analysis. The essence of this method is to study the technology as a cybernetic system with an assessment of the" reactions” of this system to external influences formed during an active experiment. At the same time, optimization problems are solved analytically. Analytical optimization is based on two main principles. The regression equations obtained as a result of processing experimental data and testing statistical hypotheses are models that adequately describe real processes. Each of these equations is an algebraic function of several variables, to which methods of mathematical analysis are applicable, including the study of extremums of functions in partial derivatives. The next step is to develop a process algorithm and develop computer programs that allow you to select the composition and predict the properties of the product. As an engineering interpretation, it is possible to construct optimized nomograms that allow solving both direct and inverse problems; that is, predicting the result or selecting technological factors. The research methods described in the article are implemented in the study of technologies of cellular concrete, foam concrete, cement-polymer concrete and products made of mineral wool and foam glass. As an example, the article considers the optimization of the selection of the composition of fine-grained concrete reinforced with chopped glass fiber. The implementation of the developed method allowed us to determine the optimal value of the determining parameters, including the consumption of fiber and plasticizer, as well as to form a method for studying the properties of products.
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Khan, Kaffayatullah, Fazal E. Jalal, Mudassir Iqbal, Muhammad Imran Khan, Muhammad Nasir Amin, and Majdi Adel Al-Faiad. "Predictive Modeling of Compression Strength of Waste PET/SCM Blended Cementitious Grout Using Gene Expression Programming." Materials 15, no. 9 (April 23, 2022): 3077. http://dx.doi.org/10.3390/ma15093077.
Повний текст джерелаАнотація:
The central aim of this study is to evaluate the effect of polyethylene terephthalate (PET) alongside two supplementary cementitious materials (SCMs)—i.e., fly ash (FA) and silica fume (SF)—on the 28-day compressive strength (CS28d) of cementitious grouts by using. For the gene expression programming (GEP) approach, a total of 156 samples were prepared in the laboratory using variable percentages of PET and SCM (0–10%, each). To achieve the best hyper parameter setting of the optimized GEP model, 10 trials were undertaken by varying the genetic parameters while observing the models’ performance in terms of statistical indices, i.e., correlation coefficient (R), root mean squared error (RMSE), mean absolute error (MAE), comparison of regression slopes, and predicted to experimental ratios (ρ). Sensitivity analysis and parametric study were performed on the best GEP model (obtained at; chromosomes = 50, head size = 9, and genes = 3) to evaluate the effect of contributing input parameters. The sensitivity analysis showed that: CS7d (30.47%) > CS1d (28.89%) > SCM (18.88%) > Flow (18.53%) > PET (3.23%). The finally selected GEP model exhibited optimal statistical indices (R = 0.977 and 0.975, RMSE = 2.423 and 2.531, MAE = 1.918 and 2.055) for training and validation datasets, respectively. The role of PET/SCM has no negative influence on the CS28d of cementitious grouts, which renders the PET a suitable alternative toward achieving sustainable and green concrete. Hence, the simple mathematical expression of GEP is efficacious, which leads to saving time and reducing labor costs of testing in civil engineering projects.
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Caballero, William N., Florian Jaehn, and Brian J. Lunday. "Transportation Labor Cost Reduction via Vehicle Platooning: Alternative Models and Solution Methods." Transportation Science, July 20, 2022. http://dx.doi.org/10.1287/trsc.2022.1151.
Повний текст джерелаАнотація:
The advent of automated and semiautomated driving technologies is prompting a reevaluation of the benefits of truck platooning. Whereas the effect of truck platooning on fuel costs is relatively well studied, automated driving enables further cost reductions in the form of labor savings that has, heretofore, been sparingly investigated. The degree to which such savings can be realized depends upon myriad factors. Foremost among them are driver payment policies and platoon formation procedures. Automated driving technology reduces the demands on a platoon’s follower vehicles, which, in turn, justifies modified driver compensation structures. However, reductions in labor expenditures are often limited by load characteristics that inhibit platoon formation. Therefore, this research sets forth a suite of related truck platooning problems that correspond to alternative assumptions about unloaded-truck compensation and shipment temporal flexibility. The computational complexities of these problem variants are examined, [Formula: see text]-hardness is proved for the suite, and other useful mathematical properties are derived. Extensive empirical testing using the U.S. highway system explores the effect of network topology, commerce flow, and platooning labor savings on each problem’s optimal solution, tractability, and other related metrics. Multiple heuristics are also designed and tested for larger-scale instances. In so doing, this research not only explores the effects of varied factors on platooning labor costs but it also provides practical means to identify high-quality, labor-cost-reducing routes.
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Gally, Tristan, Peter Groche, Florian Hoppe, Anja Kuttich, Alexander Matei, Marc E. Pfetsch, Martin Rakowitsch, and Stefan Ulbrich. "Identification of model uncertainty via optimal design of experiments applied to a mechanical press." Optimization and Engineering, February 23, 2021. http://dx.doi.org/10.1007/s11081-021-09600-8.
Повний текст джерелаАнотація:
AbstractIn engineering applications almost all processes are described with the help of models. Especially forming machines heavily rely on mathematical models for control and condition monitoring. Inaccuracies during the modeling, manufacturing and assembly of these machines induce model uncertainty which impairs the controller’s performance. In this paper we propose an approach to identify model uncertainty using parameter identification, optimal design of experiments and hypothesis testing. The experimental setup is characterized by optimal sensor positions such that specific model parameters can be determined with minimal variance. This allows for the computation of confidence regions in which the real parameters or the parameter estimates from different test sets have to lie. We claim that inconsistencies in the estimated parameter values, considering their approximated confidence ellipsoids as well, cannot be explained by data uncertainty but are indicators of model uncertainty. The proposed method is demonstrated using a component of the 3D Servo Press, a multi-technology forming machine that combines spindles with eccentric servo drives.
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Sagar, Prem, and Amit Handa. "Prediction of wear resistance model for magnesium metal composite by response surface methodology using central composite design." World Journal of Engineering ahead-of-print, ahead-of-print (December 7, 2020). http://dx.doi.org/10.1108/wje-08-2020-0379.
Повний текст джерелаАнотація:
Purpose In recent days, friction stir processing (FSP) has emerged as a pioneering approach for the manufacture of composites with enhanced mechanical and tribological properties. The present study aims to examine the impact of process parameters such as tool rotation speed and number of FSP pass on the AZ61A/TiC magnesium metal composite for responses such as hardness and wear resistance. Design/methodology/approach To minimize number of experimental runs, design of experiment was configured according to the response surface methodology using central composite design. Analysis of variance has been conducted to develop mathematical and empirical model for studying relationship between tool rotation and number of pass for responses such as microhardness and wear resistance. Microhardness was checked on vickers microhardness testing machine, and tribological behavior were examined on pin-on-disc using tribotester. Wear morphology was analyzed via scanning electron microscopy. Findings The responses were predicted using validated mathematical model, and contour plots were generated to study the interaction and influence of process parameters. Wear observations suggest that for the base magnesium alloy adhesive wear mechanism was dominating and for the developed nanocomposites, abrasive wear mechanism is a prominent factor. It was also observed that both the selected parameters significantly influenced the responses. Originality/value To the best of the authors’ knowledge, no prior work has been conducted with this material and preparation of composites with TiC nanoparticles. Furthermore, no mathematical models have been developed to predict the response values.
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"Investigations of the algorithms linear properties for strapdown inertial navigation systems." Automation. Modern Techologies, 2022. http://dx.doi.org/10.36652/0869-4931-2022-76-1-35-43.
Повний текст джерелаАнотація:
The basic operation principles of the strapdown inertial navigation systems (SINS) without platform and models of the measuring sensors errors, including offsets of zero signals, errors of scale factors and cross-links connections, are considered. The influence of various components of these errors and their linear combinations on the numeration accuracy of coordinates, velocity and orientation angles is investigated by the method of mathematical modeling of the SINS operation at one and a half hour intervals. To assess the linear properties of SINS algorithms, a quantitative measure is introduced — the value of the numeration error deviation, caused by a linear combination of input errors, relative linear combination of errors caused by separate input errors, as a percentage is expressed. Numerical estimates for typical trajectories of a maneuverable aircraft are obtained for this value. The obtained results can serve as the basis for the formation of technical requirements, used at the design and testing of aviation navigation systems and complexes. Keywords strapdown inertial navigation system, potential of the gravity field, gravitational acceleration, apparent acceleration, numeration errors, math modeling
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Liptai, Laura L. "Forensic Engineering Analysis Of Impacts To The Adult And Pediatric Head." Journal of the National Academy of Forensic Engineers 30, no. 1 (January 1, 2013). http://dx.doi.org/10.51501/jotnafe.v30i1.790.
Повний текст джерелаАнотація:
This Reports Forensic Engineering Analysis Of Impacts To The Adult Head And Pediatric Head From Multiple Sources, With The Goal Of Amassing A Database To Be Utilized For Forensic Biomedical Engineering Analysis. Supplemental Impact Activities (Of Acceleration Verses Time Data), Rather Than Cumulative Historical Adult And Child Head Impacts Are Discussed. Adult Head Impacts Recently Tested Include Motorcycle, Bicycle And Equestrian Helmeted Impacts. Infant Head Impacts Include Falls Onto Carpet/Tile And Toy Impacts, And Child Head Impacts Include Recreational Ball Tests (Baseballs, Soccer Balls, Playground Balls And Basketballs). Biomedical Engineers Use Computational Modeling And Simulation To Analyze Injurious Trauma To The Human Head And Brain. The Verification Of These Mathematical Models, Codes, Solutions, And/Or Simulations Depends Upon The Quality Of Their Experimental Validation. The Reliability Of The Experimental Data Determines The Validity Of The Modeling. A Database Of Real World Head And Brain Impact Responses Is Constructed Utilizing Principals From Biomedical Engineering, Biomechanics And Anthropometric Dummy Testing. The Digital Data Is Collected According To A Standardized Protocol Using A Tri-Axial Accelerometer Mounted Inside Of Various Anthropometric Dummy Craniums Of Infants, Children And Adults. The Performance Of Motorcycle, Bicycle And Equestrian Helmet Types Is Analyzed With Some Unexpected Results. Other Data Includes Pediatric Experimental Results That Have Not Been Previously Reported: Child Head Impacts With Various Sports Equipment, Infant Head Impacts To Surfaces Commonly In The Home, Like Tile And Carpet, As Well As Infant Head Impacts With Massive, Hard Plastic Toys. The Objective Is To Quantify The Pediatric And Adult Human Head Responses In The Form Of Acceleration Verses Time Data To Impact And Non-Impact Scenarios. This Data Will Supplement The Forensic Engineering Experimental Analysis Database As Well As Define Variables Utilized In The Mathematical Modeling Of Injurious Head Impacts To Improve Head Impact Safety Counter Measures.
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Forsdyke, Jessica C., and Janet M. Lees. "Model fitting to concrete carbonation data with non-zero initial carbonation depth." Materials and Structures 56, no. 1 (January 27, 2023). http://dx.doi.org/10.1617/s11527-023-02104-0.
Повний текст джерелаАнотація:
AbstractCarbonation is a key mechanism for deterioration of reinforced concrete structures. In design for resistance to carbonation, the performance of mixes is often specified and measured in laboratory carbonation tests where initial carbonation is sometimes present in specimens. The coherent interpretation of results from carbonation tests is vital as they enable a more accurate prediction of the performance of concrete structures in situ. This paper assesses two different approaches to considering the initial carbonation depth when extracting the carbonation coefficient from results of carbonation testing. Experimental data is compared to models for either approach using least squares regression. Both linear and non-linear representations of the initial carbonation depth are shown to fit the data well. The non-linear approach gives a larger estimate of carbonation coefficient than the linear approach, and is more consistent with the mathematical derivation of the carbonation equation. The ramifications of this difference will be most significant when the initial carbonation depth is large relative to the depth of the carbonation front. The accurate modelling of carbonation progression underpins performance-based design of new concrete structures and the assessment of existing concrete infrastructure.
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Czachorski, Robert. "Modeling Rainfall–Runoff Responses and Antecedent Moisture Effects Using Principles of System Identification." Journal of Water Management Modeling, 2022. http://dx.doi.org/10.14796/jwmm.c482.
Повний текст джерелаАнотація:
Rainfall–runoff dynamics of surface water, combined sewer, and separate sewer systems can be highly impacted by antecedent moisture conditions, or the relative wetness or dryness of the system. Accurately simulating these dynamics is critical for developing predictive models of systems that are sensitive to antecedent moisture. This paper presents the results of 25 years of work formulating, applying and refining a hydrologic model that addresses the impacts of antecedent moisture conditions on the rainfall–runoff process. The development, process and equations of the model are presented. The model was derived using the principles of system identification from the field of aerospace control systems to find the simplest mathematical model that accurately describes the relationship between system inputs and the flow output. Developing and testing the model was done primarily from observations in the U.S. Midwest. where both preceding rainfall and seasonal hydrologic conditions impact antecedent moisture dynamics. For these systems, the model described here is perhaps the most parsimonious that can accurately simulate these dynamics. This provides several advantages to the modeler, including ease of use, fewer parameters to calibrate, ability to quickly identify optimal parameters, and ease of representation in a numerical computer routine. Physical interpretation of the model structure and parameters is possible, providing the modeler with useful insights into the physical processes driving the rainfall–runoff dynamics.
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Van Den Einde, Lelli, Joel P. Conte, José I. Restrepo, Ricardo Bustamante, Marty Halvorson, Tara C. Hutchinson, Chin-Ta Lai, et al. "NHERI@UC San Diego 6-DOF Large High-Performance Outdoor Shake Table Facility." Frontiers in Built Environment 6 (January 12, 2021). http://dx.doi.org/10.3389/fbuil.2020.580333.
Повний текст джерелаАнотація:
Since its commissioning in 2004, the UC San Diego Large High-Performance Outdoor Shake Table (LHPOST) has enabled the seismic testing of large structural, geostructural and soil-foundation-structural systems, with its ability to accurately reproduce far- and near-field ground motions. Thirty-four (34) landmark projects were conducted on the LHPOST as a national shared-use equipment facility part of the National Science Foundation (NSF) Network for Earthquake Engineering Simulation (NEES) and currently Natural Hazards Engineering Research Infrastructure (NHERI) programs, and an ISO/IEC Standard 17025:2005 accredited facility. The tallest structures ever tested on a shake table were conducted on the LHPOST, free from height restrictions. Experiments using the LHPOST generate essential knowledge that has greatly advanced seismic design practice and response predictive capabilities for structural, geostructural, and non-structural systems, leading to improved earthquake safety in the community overall. Indeed, the ability to test full-size structures has made it possible to physically validate the seismic performance of various systems that previously could only be studied at reduced scale or with computer models. However, the LHPOST's limitation of 1-DOF (uni-directional) input motion prevented the investigation of important aspects of the seismic response of 3-D structural systems. The LHPOST was originally conceived as a six degrees-of-freedom (6-DOF) shake table but built as a single degree-of-freedom (1-DOF) system due to budget limitations. The LHPOST is currently being upgraded to 6-DOF capabilities. The 6-DOF upgraded LHPOST (LHPOST6) will create a unique, large-scale, high-performance, experimental research facility that will enable research for the advancement of the science, technology, and practice in earthquake engineering. Testing of infrastructure at large scale under realistic multi-DOF seismic excitation is essential to fully understand the seismic response behavior of civil infrastructure systems. The upgraded 6-DOF capabilities will enable the development, calibration, and validation of predictive high-fidelity mathematical/computational models, and verifying effective methods for earthquake disaster mitigation and prevention. Research conducted using the LHPOST6 will improve design codes and construction standards and develop accurate decision-making tools necessary to build and maintain sustainable and disaster-resilient communities. Moreover, it will support the advancement of new and innovative materials, manufacturing methods, detailing, earthquake protective systems, seismic retrofit methods, and construction methods. This paper will provide a brief overview of the 1-DOF LHPOST and the impact of some past landmark projects. It will also describe the upgrade to 6-DOF and the new seismic research and testing that the LHPOST6 facility will enable.